Ms Hubbard said a blood clot was removed from his brain, and a section of skull taken out to provide space for the swelling of the brain.
The temporary opening of the skull reduces pressure, allowing better blood flow and promoting healing.
The stroke had left Mr Mulu paralysed on the right side of his body and unable to speak, but yesterday he uttered his first, mumbled words.
"We are trying to get him to count," Ms Hubbard said. "That's the first time he's been able to do that [since the stroke]. He is very agitated because he can't communicate with us through talking.
"When we first got into Auckland Hospital they gave him a 15 per cent chance that he was going to survive. That was with surgery. I was freaked out."
The risk of another stroke was high at first, but he had since passed that point and was making rapid progress.
"He is able to sit up, even with only half his body working. He's doing pretty well, but he's got a long, long, long road ahead of him to get any better."
A previously undiagnosed kidney problem was found during his hospital stay but it is not yet known whether it was a cause or consequence of the stroke.
Mr Mulu, a permanent resident, moved from Samoa to New Zealand in 2009 and works as a bedmaker at the Otahuhu Sleepyhead factory.
"He's our sole provider," said Ms Hubbard, who also has two daughters. A Givealittle fundraiser has been set up to ease the family's financial stress.
The Stroke Foundation says strokes in the young tend to be caused by non-preventable factors, such as a weakness in the wall of a blood vessel that has been present since birth.
To donate, see givealittle.co.nz/cause/help4tali
